This renewal application builds on the expertise of an experienced and dedicated faculty with a 23-year history of leading successful AHRQ-funded, post-doctoral NRSA training programs focused specifically on pediatric health services research. In an increasingly dynamic US health care system, meeting the needs of children will require health services researchers to be trained in novel and wide-ranging methods to study and improve the effectiveness, efficiency, and equity of health care. Through expanding faculty and partnerships, our program stands ready to meet the needs of our trainees to tackle health services research that builds on advances in science, technology, and data analytics, including genomics; data mining and machine learning; novel diagnostics and therapeutics; and information technology. In this renewal, we will continue the core programmatic collaborations among Boston Children's Hospital, the MassGeneral Hospital for Children, and the Department of Population Medicine at Harvard Medical School as well as the successful engagement of our newest partner?the Institute for Healthcare Improvement?which has brought its recognized expertise in care improvement and implementation science to our trainees through curricular enhancements and research opportunities. As both the development of research and its implementation are increasingly informed by patients and the patient experience, our program will continue to engage patients and parents to provide substantive feedback on trainees' current and future research, as an integral aspect of our program's culture. For this renewal, we will also engage with new partners to address the expanding role of information technology in healthcare. Our program will focus on four pillars of training: 1) cutting edge observational methods to learn from health and health system data; 2) application of implementation science and related methods to improve the design, delivery, and evaluation of care for children across a variety of financing and delivery systems; 3) incorporating the perspective of patients and families into the process for designing and conducting research; and 4) framing research in children as a part of health over the life course, especially the pervasive, enduring impact of disparities in care and services. The program will support 6 stipends per year (3 first-year and 3 second-year continuing postdoctoral fellows) to create a critical mass of trainees across subspecialties, areas of research, and methodological domains. In addition to conducting closely mentored research, each trainee will complete the requirements of an MPH from the Harvard T.H. Chan School of Public Health for core skills of biostatistics and epidemiology, and participate in advanced health services research methods training. Our well-developed program infrastructure and system for close monitoring of trainees' progress will ensure the continuation of our record of graduating individuals who will lead relevant, applied health services research that translates into both improved care and health outcomes for all children.